Simvastatin alleviates inflammation and oxidative stress in rats with cerebral hemorrhage through Nrf2-ARE signaling pathway

C.-Y. Zhang, X.-M. Ren, H.-B. Li, W. Wei, K.-X. Wang, Y.-M. Li, J.-L. Hu, X. Li

Department of Emergency, First Affiliated Hospital of Jiamusi University, Jiamusi, China. 15694548231@163.com

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• Pharmacology

OBJECTIVE: To investigate the regulatory effects of simvastatin on the inflammation and oxidative stress in rats with cerebral hemorrhage through the nuclear factor E2-related factor 2-antioxidant response element (Nrf2-ARE) signaling pathway.

MATERIALS AND METHODS: A total of 120 healthy male rats weighing 280-300 g and 7-8 weeks old were selected to establish the traumatic brain injury (TBI) model. Rats were divided into group A (trauma operation, n=30), group B (no treatment, n=30), group C (drug administration after trauma operation, n=30), and group D (no trauma operation, drug administration, n=30). Cerebral edema content in brain tissues was measured by calculating the dry and wet weight. Neurological dysfunction was scored using the Garcia method. Positive levels of the Toll-like receptor 4 (TLR4) and interleukin-1β (IL-1β) were qualitatively analyzed via immunohistochemistry. Protein levels of TLR4 and IL-1β were quantitatively analyzed via Western blotting. Moreover, the brain injury volume and neuronal apoptosis were evaluated via Nissl staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, respectively. At 48 h after injury, activities of superoxide dismutase (SOD), reduced glutathione (GSH), and oxidized glutathione (GSSG) in brain tissues were detected, and levels of malondialdehyde (MDA) and nitric oxide (NO) were detected using the enzyme activity assay kits. Finally, relative levels of the Nrf2-ARE signaling pathway and its downstream molecules heme oxygenase-1 (HO-1) and NAD (P)H dehydrogenase, quinone 1 (NQO1) were detected via reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting.

RESULTS: Compared with those in group B, cerebral edema content in brain tissues significantly increased (p<0.05), the neurological dysfunction score significantly declined (p<0.05), and protein levels of TLR4 and IL-1β were significantly upregulated in group A (p<0.05). In group C, relative levels of TLR4 and IL-1β were down-regulated, cerebral edema content decreased, and the neurological dysfunction score significantly increased (p<0.05). After 48 h, activities of SOD, reduced GSH and GSSG and levels of MDA and NO all increased, and levels of MDA and NO declined in group C (p<0.05). Western blotting and RT-PCR showed that simvastatin could increase the transcriptional level of Nrf2. After simvastatin intervention, expression levels of downstream molecules HO-1 and NQO1 were upregulated.

CONCLUSIONS: Simvastatin alleviates TLR4-mediated inflammatory injury, promotes neurological recovery and resists oxidative stress through the Nrf2-ARE signaling pathway, thus exerting a neuroprotective effect in TBI.

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